Speaker
Description
The code of practice (TRS398 and TG51) for the determination of the absorbed dose to water recommend the use of the two-voltage method (TVM) for the calculation of the ion recombination correction factor, which is based on the early Boag theory and do not take into account the contribution of free electrons to the ionization chamber signal. Later, Boag and contemporaries developed three additional models that exhibit inconsistency even in the conventional dose per pulse regime.
A detailed numerical simulation of the charge carrier transport inside a parallel plate ionization chamber (PPIC) was developed in order to obtain the dynamical response of a PPIC.
Experimental data on saturation factor obtained for two Advanced Markus and PPC05 chambers at the 20 MeV PTB MELAF electron beam has been successfully compared with the numerical simulation providing evidence of the limited validity of the TVM.
